Compressor unloader



COMPRES SOB UNLOADER Filed Sept. 14, 1929 IN VENTOR.

H15 ATTORNEY.

Patented Mar. 17,193]

UNITED STATES PATENT OFFICE JOHN LE VALLEY, on PAINTED rosr,

NEW YORK, ASSIGNOR T INGERSOLL-RAND COMPANY, OF JERSEY CITY, NEW JERSEY,A CORPORATION OF NEW JERSEY COMBR-ESSOR UNLOADER Application filedSeptember 14, 1929. Serial No. 392,695.

This invention relates to compressors, but more particularly to acompressor unloader adapted to automatically unseat the inlet valve orvalves of compressors whenever the pressure in the receiver into whichthe compressor discharges reaches a certain predetermined value.

One object of the invention is to prevent communication between thecylinder of the compressor and the channels through which air isconveyed to the cylinder.

Another object is to protect the unloadcr and cooperating elementsagainst severe jars or strains by suitable cushioningmcans whichWill-yield gradually to the pressure for actuating the unloader.

Other objects will be in part obvious and in part pointed out.hereinafter-a The figure in the accompanying drawin is applied asectional elevation of a compressor unloader constructed in accordancewith the practice of-the invention and showing the unloader applied to acompressor.

Referring more particularly to the drawing, A represents: a portion of acompressor cylinder having a compressor chamber B in which is disposed apiston C. A. closure is provided for the compressor chamber 13 by a headI) which may be secured to the cylinder in any suitable and convenientmanner.

The cylinder A comprises an inner wall E and an outer wall F spaced withrespect to the wall E to to m therebetween a passage G through whichair, either compressed air from a lower sta e c linder or atmos )hericair, may flow to the compressor chamber B.

The walls E and F are provided With aper tures H and J respectivelywhich are aranged coaxially with respect to each other.

The aperture H is adapted to accommodate valve mechanism designatedgenerally by K, and comprising a valve seat L which seats against thewall E and in this instance has seating surfaces 0 and P at oppositeends. In the valve seat L is a port or ports Q through which the airfrom the passage G on ters the compressor chamber B. The outlet end B ofthe port Q is controlled in this instance by a valve plate S whichcooperates With the seating surface 0 for this purpose and is urgedthereagainst by a spring T interposed between the valve plate S and astop plate U which may be secured to the valve seat in any suitablemanner, as by a bolt W and a nut X In order to conveniently hold thevalve assembly in the aperture H an unloader cylinder Y is threaded intothe aperture J and said unloader cylinder carries at its inner end askirt Z adapted to bear against the valve seat L. In this skirt areformed ports I) to afford free communication. between the passage G andthe port Q, in the valve seat,

In addition to the function described, the unloaded. cylinder Y alsoserves as a housing for unloading devices intended to selectively cutoil communication between the port Q and the passage G. To this end thecylinder Y is provided with a bore 0 to slidably receive a hollowplunger d. The bore 0 extends entirely through the unloader cylinder Y,although the inner portion, that is, the portion adjacent the skirt Z isof somewhat reduced diameter as at e to accommodate a reduced extensionf of the plunger (Z. In this way is formed a shoulder g in the bore 0which may act as a stop for a shoulder it on the plunger (Z in order toassure the retention of the plunger in the bore, particularly during theassembly of the device in the compressor.

Secured to the outer end of the unloader cylinder, as by means of boltsj, is a cover I: which forms a closure for the bore 0, and said cover itis n'eferably provided with a cavity 0 to serve as a chamber into whichpressure fluid from a suitable source of supply may be introduced intothe end of the bore 0 for depressing the plunger (Z. For this purpose apipe 1] is threaded into the cover is.

The cavity Q in the plunger (Z is adapted to accommodate slidably avalve 1* of cup shape having a hollow body portion .5- and at its openend a lateral flange t to cooperate with the seating surface P forclosing the inlet end oi the port Q In order to normally assure theretractul positions of the plunger (Z and the valve 7*, a spring o isdisposed Within the plunger (3 to bear against the end of the valve 1",and a spring w is interposed between the valve seat L and the valve 1".

Any suitable and well known means, as for instance, an auxiliary valve(not shown) may be interposed in the pipe p for automaticallycontrolling the admission of pressure fluid into thechamberro, when thereceiver pressure exceeds a certain predetermined value, and toautomatically exhaust such pressure fluid from the chamber 0 after thepressure in the storage receiver has again dropped below that which itis desired to maintain.

During the normal operation of the comoressor, as when the compressor isoperating under full load conditions,'the plunger cl and the valve 1"will beheld in the retracted position by the springs '12 and w. Air willthen flow from the passage G through the port Q and into the chamber Bwhere it will be compressed by the piston C. This operation may continueuntil the pressure in the storage receiver into which the compressordischarges reaches a maximum value which it is desired to maintaintherein and at which such controllingdevices as may be interposed in thepipe p are adapted to act for unloading the compressor.

Whenever this pressure has been attained, pressure fluid will beadmitted into the pressure chamber 0 to act against the plunger cl. andto move the plunger in the direction of the valve assembly. The movementof the plunger will be transmitted through the spring oto the valve 1"and the spring w will then also act to resist the movement, of theplunger as well as the movement of the valve 7. The plunger and thevalve will however be moved inwardly until the flange 27 seats againstthe seating surface P to close the inlet opening of the valve may bereached withoutcompressing the spring 0 to such an extentwhere theinnermost end of the reduced portion f of the plunger will contact withthe flange t, depending, of course, upon the tension of the spring o.The plunger may however be pressed into body contact with the flange tto hold the valve r in the closed position until the receiver pressurehas again been decreased below the maximum pressure at which theunloader is intended to act. When this condition in the receiver obtainsthe means provided for automatically releasing the pres sure fluid inthe chamber 0 may then act and the plunger cl and the valve 4 will a ainbe restored to the retracted positionsdoy the springs actingthereagainst.

I claim: a

1. A compressor unloader, comprising a valve seat having a port, a valveplate for controlling one end of theport, an unloader ed plungertherein,

cylinder over the valve seat, a pressure actuata valve slidable in theplungerv and adapted to seat over the other port Q. This pressure of theend of the port, and a spring between the plunger and the valve fortransmitting the movement of the plunger to the lastsaid valve.

2. A. compressor unloader, comprising a valve seat having a port, avalve plate for controlling the outlet end of the port, an unloadercylinder over the valve seat, a pressure actuated plunger therein, avalve slidable in the plunger and adapted to seat'over the inlet end ofthe port, and a spring between the plunger and valve for causing thelast said valve to follow the movement of the plunger.

3. A compressor unloader, comprising a valve seat having a'port, a valveplate for controlling the outlet end of the port, an unloader cylinderover the valve seat, a pressure actuated plunger therein, a valve slidable in the'plunger and havinga flange adapted to seat over the inletend of the port, a spring between the plunger and valve for transmittingthe movement of the plunger to the last said valve, and a second springbetween the valve plate and the valve to normally maintainfthe valvefree. from the valve seat. v

4. A compressor unloader, comprising a valve seat having a port, a'valveplate for controlling the outlet end of the port, an unloader cylinderover the valve seat, a pressure actuated plunger therein, a cup-shapedvalve slidable in the plunger and having a flange at its open endadapted to seat over the inlet end of the port, a spring in the plungerabutting the closed end of the valve for transmitting the movement ofthe plunger to the last said valve, and a second spring positioned inthe cup-shaped valve and abutting the valve plate to normally maintainthe valve free from the valveseat In testimony whereof I have signedthis specification. v T

JOHN LE VALLEY.

